Be successful with a superior suit (5)
I believe the answer is:
trump
'suit' is the definition.
(I know that trump is a type of suit)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for trump that I've seen before include "club perhaps" , "Outplay" , "Card of designated top suit" , "Surpass" , "Powerful card - the last one to be heard at the Day of Judgement" .)